The major industrial applications for hydrolases, e.g., esterases, lipases, phospholipases and proteases, include the detergent industry, where they are employed to decompose fatty materials in laundry stains into easily removable hydrophilic substances; the food and beverage industry where they are used in the manufacture of cheese, the ripening and flavoring of cheese, as antistaling agents for bakery products, and in the production of margarine and other spreads with natural butter flavors; in waste systems; and in the pharmaceutical industry where they are used as digestive aids.
Oils and fats an important renewable raw material for the chemical industry. They are available in large quantities from the processing of oilseeds from plants like rice bran oil, rapeseed (canola), sunflower, olive, palm or soy. Other sources of valuable oils and fats include fish, restaurant waste, and rendered animal fats. These fats and oils are a mixture of triglycerides or lipids, i.e. fatty acids (FAs) esterified on a glycerol scaffold. Each oil or fat contains a wide variety of different lipid structures, defined by the FA content and their regiochemical distribution on the glycerol backbone. These properties of the individual lipids determine the physical properties of the pure triglyceride. Hence, the triglyceride content of a fat or oil to a large extent determines the physical, chemical and biological properties of the oil. The value of lipids increases greatly as a function of their purity. High purity can be achieved by fractional chromatography or distillation, separating the desired triglyceride from the mixed background of the fat or oil source. However, this is costly and yields are often limited by the low levels at which the triglyceride occurs naturally. In addition, the purity of the product is often compromised by the presence of many structurally and physically or chemically similar triglycerides in the oil.
An alternative to purifying triglycerides or other lipids from a natural source is to synthesize the lipids. The products of such processes are called structured lipids because they contain a defined set of fatty acids distributed in a defined manner on the glycerol backbone. The value of lipids also increases greatly by controlling the fatty acid content and distribution within the lipid. Lipases can be used to affect such control.
Phospholipases are enzymes that hydrolyze the ester bonds of phospholipids. Corresponding to their importance in the metabolism of phospholipids, these enzymes are widespread among prokaryotes and eukaryotes. The phospholipases affect the metabolism, construction and reorganization of biological membranes and are involved in signal cascades. Several types of phospholipases are known which differ in their specificity according to the position of the bond attacked in the phospholipid molecule. Phospholipase A1 (PLA1) removes the 1-position fatty acid to produce free fatty acid and 1-lyso-2-acylphospholipid. Phospholipase A2 (PLA2) removes the 2 fatty acid to produce free fatty acid and 1-acyl-2-lysophospholipid. PLA1 and PLA2 enzymes can be intra- or extra-cellular, membrane-bound or soluble. Intracellular PLA2 is found in almost every mammalian cell. Phospholipase C (PLC) removes the phosphate moiety to produce 1,2 diacylglycerol and phospho base. Phospholipase D (PLD) produces 1,2-diacylglycerophosphate and base group. PLC and PLD are important in cell function and signaling. Patatins are another type of phospholipase thought to work as a PLA.
In general, enzymes, including hydrolases such as esterases, lipases and proteases, are active over a narrow range of environmental conditions (temperature, pH, etc.), and many are highly specific for particular substrates. The narrow range of activity for a given enzyme limits its applicability and creates a need for a selection of enzymes that (a) have similar activities but are active under different conditions or (b) have different substrates. For instance, an enzyme capable of catalyzing a reaction at 50° C. may be so inefficient at 35° C., that its use at the lower temperature will not be feasible. For this reason, laundry detergents generally contain a selection of proteolytic enzymes, allowing the detergent to be used over a broad range of wash temperature and pH. In view of the specificity of enzymes and the growing use of hydrolases in industry, research, and medicine, there is an ongoing need in the art for new enzymes and new enzyme inhibitors.